The turbo filter is intended to filter liquid products containing insoluble solid particles, and in its traditional construction, prior to that of patent applications referred to above, such as the one, for example, of PI 9201898-0, of Apr. 24, 1992, it essentially comprises a filter body provided with an intermediate filtrating chamber with extreme feeding inlet, lower filtrate outlet and opposite extreme solid outlet; a filtrating element in the form of cylindrical filtrating sleeve, made in technical cloth laid out inside and along the filtrating chamber and connected to its inlet and outlet by a rotor placed inside and along the filtrating sleeve and provided with two sets of helical paddles, a set of fine step paddles that provides axial impulse and no radial impulse for the product, which defines an inlet state for the product to be filtrated, and a set of coarse step paddles provided with convex dragging surface, which gives a great radial impulse and a small axial one, which defines the processing stage in which the product outflows in the form of growing vortex between the inlet and outlet and close to the internal face of the filtrating sleeve, providing simultaneously the filtration and the self-cleaning effect by sleeve washing, the main functional features of the turbo filter and which made it known to users; an elastic support for the filtrating sleeve, which allows it to extend radially and shrink axially in the pressure peaks, so as not to deform or break, and return to the normal share upon the end of overpressure; a filtrating sleeve washing device; a motor set to drive the rotor and others.
With the continuity of studies on the filtration of liquid products with insoluble suspended solids, the turbo filter inventor conceived an innovating filtration system, according to which the retaining capacity, as to the lower size of the solid particle to be retained, is determined mainly by the angular position among the filtrating element vents and the directions of flows of the product to be filtrated, which cross the vents; said angular position is selected for the orthogonal projection of a vent in a plane perpendicular to the corresponding flow of product to be filtered, which crosses said vent, be smaller than the least particle of the insoluble solid to be retained. Such a process is performed by a turbo filter provided with specific improvements, as per the patent application PI 0700933-0, referred to above.
By continuing the studies, the inventor conceived an improved metallic filtrating body object of CI 0700933-0, to be used in the turbo filter that performs the new filtration process informed by PI 0700933-0. Such a metallic filtrating body is substantially a tubular metallic grid formed by a number of thicker reinforcement bars parallel to each other, and a number of thinner parallel stems, placed perpendicularly to the bars and welded to the same, with the spaces defined by said bars and stems constituting the filtrating vents in the filtrating body constituted by the grid.
Such a filtrating body construction works properly, but studies performed show it is liable to be improved, mainly when the turbo filter performs filtrating processes of liquid products with high contents of abrasive suspended solids, such as informed in the patent application PI 1005744-7 by the same inventor.
In fact, said studies show that in given types of filtration, for example when the product presents high contents of abrasives, as in case of sugar came syrups, the whole turbo filter set can be very demanded, mainly the filtrating element, which must be efficient to retain the solid phase and let the liquid phase of product pass, and therefore, even though it is metallic, it is severely attacked by the eventual abrasiveness of the product.